CVE-2026-27143: Missing bound checks can lead to memory corruption in safe Go in cmd/compile

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-08 · updated 2026-07-25

Description

Arithmetic over induction variables in loops were not correctly checked for underflow or overflow. As a result, the compiler would allow for invalid indexing to occur at runtime, potentially leading to memory corruption.

Affected products

Go: before 1.25.9; from 1.26.0 before 1.26.2 — fixed in 1.25.9, 1.26.2

How to fix

Upgrade to a fixed version: Go 1.25.9, 1.26.2. Check the vendor advisory for mitigations.

References

https://go.dev/cl/763765
https://go.dev/issue/78333
https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU
https://pkg.go.dev/vuln/GO-2026-4868

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